DESCRIPTION: The recently discovered HSV-1 ORF-P gene almost completely overlaps the ICP34.5 gene in an antisense direction. Recent studies in the P.I.'s laboratory have shown that one or the other of these two proteins is essential for wild type levels of corneal disease, spontaneous reactivation, and neurovirulence. The specific aim is to confirm that ORF-P is important for corneal disease and spontaneous reactivation. Corneal disease and reactivation can be rescued in d34.5 (a mutant deleted for ORF-P---ICP34.5 in both long repeat) by inserting a copy of ORF-P---ICP34.5 into a novel, location in the unique long (UL) region. This novel model, eliminates mapping complications due to overlap of the LAT gene. The plans to: (a)Rescue corneal disease (and neurovirulence and spontaneous reactivation) by inserting an ORF-P---34.5 restriction fragment into UL that (i)can make the ORF-P protein (but not (ICP34.5), or (ii)can make the ICP34.5 protein, (but not ORF-P). (b)Rescue d34.5 by inserting into UL or ORF=P or ICP34.5 under control of the strong HCMV promoter. (c)Rescue d34.5 by inserting ORF-P+/ICP34.5- or ORF-P+/ICP34.5+ restriction fragments into the native ORF-P---ICP34.5 location. (d)Fine map the region(s) of ORF-P (or ICP34.5) involved in corneal disease (and spontaneous reactivation and neurovirulence).